Apparatus for igniting and operating gaseous discharge devices



Feb 7 1961 A. E. FEINBERG r-:rAL 2,971,124

APPARATUS FOR IGNITING AND OPERATING GASEOUS DISCHARGE DEVICES FiledOct. 19, 1959 2 Sheets-Sheet 2 1 *uid luffe s, 3Q,

l 'Hulwnnn 'F' CP Pl) lll mmm {www} il v (P2 l 52 43 @a L//Vf g-MQ?, ML,fda? United States Patent O F" APPARATUS FOR IGNITIN G AND OPERATINGGASEOUS DISCHARGE DEVICES Albert E. Feinberg and Paul Berger, Chicago,Ill., assignors to Advance Transformer Co., Chicago, Ill., a corporationof Illinois Filed Oct. 19, 1959, Sex'. No. 847,314

23 Claims. (Cl. 315-97) This invention relates generally to apparatuswhose purpose it is to cause ignition and operation of gaseous dischargedevices and more particularly it is concerned with the construction of aballast for such purposes and the system in which the ballast is adaptedto be used.

The invention herein is directed primarily to the solution of severalimportant problems which have arisen in recent years With the advent offluorescent lamps of ,the so-called rapidstart type, which are designedto draw relatively higher currents than usual. Such lamps draw currentsduring operation of the order of 1.5 amperes and require a considerablenumber of turns of heavy Wire in the secondary winding of transformersused to ignite and operate same. For example, the characteristics of tworelatively high-output, heavily-loaded lamps which are available at thistime are:

Lamp 1 (Power Groove) 96 T-17 Ignition voltage volts 335 Operationvoltage do-.. 175 Rated wattage watts-- 216 Rated current amparos 1.5Diameter of lamp inches-- 2% Lamp 2 (V.H.O.) 96 T-IZ `Ignition voltage Y"volts" 335 Operation voltage do 175 Rated wattage watts-- 216 Ratedcurrent aniperes-- 1.5 Diameter of lamp inches-- 11/2 Two such lamps inseries will operate at approximately 350 volts, and open circuit voltagefor such an arrangement is about 525 volts.

Probably one important cause for the problems which have arisen is thenecessity that the ballast be accommodated in a narrow cross-sectionhousing, which means that the secondary winding serving the apparatusmust be narrow and elongate. The narrow cross-section housing is usuallya channel structure which comprises a part of a fixture for fluorescentlamps. Modern fixture design in general demands that the ballasts forfluorescent lamps be as narrow as possible, and in most cases, themaximum width permitted for the ballast is somewhat more than threeinches. The proportions of the windings dictated by this requirementwill be noted hereinafter..

In any event, the problems which have arisen have not heretofore beensolved and these include the following:

a. The extreme length of the secondary means that since the couplingwith the primary decreases with the distance from the primary, there isconsiderable loss of coupling so that a larger number of turns isrequired to achieve a given open circuit voltage. The increased numberof turns increases costs, size, weight and heat. The result is that acompromise must be made, and in the past this has been achieved byoperating the ballast at reduced output, with less turns than needed.

b. The extreme length of the secondary has resulted in 2,971,124Patented Feb. 7, 1961 very high leakage reactance which distorts'theshape of the current wave and hence decreases lighting eflciency. Inaddition, the condenser which is in series with the ,lamps must be ofhigher voltage rating. Further, there .is diiculty in adjusting theleakage reactance in designing a ballast because the high value is notreadily changed merely by making changes in the core structure, and inany event, these are expensive, especially in a leading type of circuit.

c. High leakage reactance gives rise to many less important diiculties,such as circuit instability, flux fringing, noise, etc.

The primary object of the invention is the provision of apparatus whichwill obviate the diculties, but which will result in a structure whichis more economical and eificient than heretofore.

Specically, the invention achieves the following advantages:

(l) The coupling between the primary winding and secondary winding isincreased, thereby decreasing the number of turns and the amount of wireused. This provides for full output with no compromise and with reducedheating.

(2) The leakage reactance is decreased, but, because of theconstruction, is readily adjustable over wide ranges which enableseconomical laminations and condensers to be used. Furthermore, thestructure gives a high degree of flexibility to enable many designs tobe readily achieved for a single kind of core structure for differenttypes of lamps without expensive changes being made therein.

(3) The structure also provides for great flexibility in adjustabilityof coupling to enable stable and balanced arrangements to be readilymade, without increasing leakage reactance.

(4) The advantageous structure can be operated at high flux densities inthe primary Without danger of distortion of the current wave shapecaused by saturation in the secondary.

The invention is characterized by the provision of a ballast whichincludes a transformer mounted on an elongate iron core which has asecondary winding in the center thereof and with a primary windingcoaxially mounted relative to the secondary winding, but split into twoparts, with each part located on opposite sides of the secondarywinding. The central winding core has one or two bridged gaps or slotstherein arranged in a fashion to adjust the coupling between thesecondary and the respective primary parts and to adjust leakagereactance, and gapped shunts are provided between the secondary windingand at least one of the primary parts to produce proper balance andleakage reactance in the secondary. It may be said generally that theapparatus which is provided by the invention has good couplingcharacter` istics between the primary and secondary and the properleakage reactance to give good wave shape correction, increasinglighting etliciency, cutting down on the number of turns required, andwith lower heat losses.

Many objects and advantages of the invention will occur to those skilledin this art as a description of the invention proceeds, in connectionwith which the preferred embodiments have been set forth in detail, forthe most part comprising different circuit variations, but all beingassociated with the same or a similar construction of core. It is not tobe inferred that the invention is specically directed to theconstruction and arrangement of these preferred embodiments, but ratherit is to be understood that considerable variation is capable of beingmade without departing from the spirit of the invention.

In the drawings which are appended hereto:

Fig. l is a sectional View taken through a transformer which isconstructed in accordance with the teachings of the invention and whichis adapted to be incorporated into the apparatus of the invention. Afragment ofY the canister for holding the ballast is also illustrated.

'Figv 2 is a circuitdiagram illustrating the apparatusY relationship anda somewhat different arrangement offilament windings is shown.

Fig. 6 is a view similar to that of Fig. l but showing a modified formof core.

The rapid-start lamp, as known today, is a fluorescent lamp in whichthere are filaments secured in the ends of a glass envelope the walls ofwhich are coated with phosphors and the lamp containing a minutequantity of gas at 1ow pressure with a few droplets of mercury. The lampis connected into a circuit in which thellaments of the lamp arecontinuously supplied with a low current and hence the transformer whichis used to provide the igniting and operating voltages must havefilament windings. The general characteristics of the lamp are notmuchdifferent than those of other gaseous discharge devices. The lamp startsat a voltage which is substantially higher than that at which itoperates. Starting is accomplished by a break-down of the gas moleculesin the envelope, caused by the ionization thereof. At open circuit thelamp presents substantially kinfinite impedance to the flow of current,but upon ignition, thisimpedance drops to practically zero. Thetransformer which provides power for the lamp hasssutiicient leakagereactance so that the ow of current is limited when the lamp commencesto conduct.

The basic circuit used with rapid-start lamps usually includes a primaryand secondary winding connected in autotransformer relationship across apair of series-connected lamps, one of the lamps being shunted by acondenser. Upon open circuit, all of the output voltage is applied tothe lamp which does not have the condenser because the condenser acts asa conductor insofar as voltage is concerned. lgnition of the tirst lampcauses flow of current through the condenser shunting the second lamp,and the flow of current develops a voltage across the shunting condensersucient to ignite the second lamp. Thereafter current flows through bothlamps in series, there usually being a power factor condenser inserieswith the lamps to provide for a leadingv current.

As previously stated, in this invention, the primary winding is dividedinto two parts which are physically located on opposite sides of thesecondary winding, to give rise to the benefits mentioned. One or morebridged gaps are provided in the central winding leg of the core, andsuitable shunts are provided between the secondary winding and one orboth of the primary parts. As in the case of the conventional ballast,the condensers, transformer, and suitable radio interference condensersand bleed resistors, the latter two types of elements not oeing shown,are enclosed in a suitable sheet metal canister and potted in a pitchcompound, with the necessary leads extending through suitable openingsin the canister. These are connected to the lamps and the line inaccordance with specic diagrams normally carried upon the canister.

Fig. 2 illustrates a circuit diagram of the apparatus in` which theprimary parts are parallel, this structure, being designated 10, andFig. 3 illustrates a similar structure inwhich the primary parts are inseries. The same transformer 12 is used kin both cases, although as willbe4 explained, the transformer is subject to variation in its"construction.

In Fig. 1 the transformer 12 is shown to comprise a shell-type corewhich has an elongate central winding leg 14 which has a T-shapedconfiguration, the cross-bar of the T being the bridging end 16. Theside legs 18 are parallel with and spaced from the central winding leg14 to provide the elongate spaces on opposite sides of the centralwinding leg 14 which are occupied by the windings. pairs of windows, thecenter elongate window Ztl' accommodating the secondary winding S, andend windows 22 and 24 for accommodating the primary parts P1 and P2respectively, together with such of the filament windings F1, F2 and F3as. may be located in close coupled relationship with the respectiveprimary parts. Practically, the spaces between side legs 18 and thecentral winding leg 14 are continuous throughout their length, althoughthe invention contemplates that the shunts which will be described maybe formed as integral extensions, either from thc central winding leg 14directed toward the side legs 18, or from the side legs l directedvtoward the central winding leg 14. Another structure would haveportions integral with both the central winding leg 14 and the side legs18.

The side legs 1S are both of elongate L conguration, With the short legs26 extending toward one another at the right hand end of the core andabutting opposite edges of the end 28 of the central winding ieg 14 toform therewith a bridging portion opposite the end 1d. The ends 30 ofthe elongate portions of the side legs 18 abut the ends of the bridgingend 16. Preferably the central winding leg 14 has twice the width of theside legs 18; In addition, it is preferred that the laminations fromwhich the core of the transformer 12 is formed be stamped from acontinuous strip of electrical or cold rolled steel, with substantiallyno waste. note the pilot hole notches 32 and 32 and 34 and 34.

These notches would face one another in pairs if thetwo side legs 18were shifted to the right and movedl close to the edges of the centralwinding leg 1d. This arrangement of nested parts provides asubstantially rec` tangular configuration readily stamped withsubstantially no scrap from a strip of steel, either along the length ofthe strip or crosswise thereof.

The ends of the side legs 1S are notched, as at 36 to accommodate sheetmetal end clamps of any suitable construction, for holding a stack ofthe laminations to gether in the arrangement shown. lf desired, thestacks of laminations may be riveted together by suitable eyelets orrivets, in addition to or instead of the end clamps. Likewise, it iswithin the purview of the invention to utilize the so-called forced coretype of construction inV Y ponents making up the ballast.

Referring now to Figs. 2 and 3, in cach case there is a primary windingwhich is formed of a pair of parts P1 and P2 and in each case the leftterminal 4Z of the.

primary part P1 is connected by the lead da which may be the white leadto one side of a line which may be.

volts, 60 cycles A.C. in the apparatus 1t?, the right hand terminal 46of the primary part P1 is connected tu the left hand terminal of thesecondary winding S and.

also to the lead i3 whichextends from the left hand terminal of theprimary part P2.v This terminales extends by way-ofA the lead 5-whiclrmay be. a black lead, ,toi Note thatthe right hand,`

the second side of the line. terminalof the primary partizisconnected bythe lead it may be considered that there are threev For exam-ple,-

52 with the lead 44 so that electrically the two primary parts P1 and P2are in parallel, and the full line voltage is across both.

ln the apparatus 19, on the other hand, the right hand terminal of theprimary part P1 is connected by means of the lead 48 only to the lefthand terminal of the primary part P2, while the right hand terminal ofthe primary part P2 is connected by the lead 52 to the left handterminal of the secondary winding S, and by way of the conductor 5@ tothe right hand side of the line. Thus, the primary parts P1 and P2 ofap,- paratus are connected in series. Obviously, in both cases, each ofthe primary parts is connected in voltage aiding relationship with thesecondary winding S, but only in the apparatus 10 are the primary partsP1 and P2 in voltage aiding relation to one another. In apparatus 10,since the primary parts P1 and P2 are in parallel with one another, thesame voltage is applied across both, and the load voltage is the voltageof S added to the voltage across either of these parts. Primary parts P1and P2 of apparatus 10 share the total line voltage across 44 and Sti sothat in this case the load voltage is the voltage of S added to thevoltages of both of the primary parts. In either case, the secondarywinding S has a voltage greater than the total primary voltage and assuch may be considered in voltage step-up relationship with the primarywinding.

in all other respects, the two apparatuses are equivalent. Thus, eachhas the filament windings F1 and F2 closely coupled with the primarypart P1 and the filament winding F3 closely coupled with the primarypart P2. Filament windings F1 are connected by leads 56 and 58 to thelett hand larnents 65B of the lamps L1. Filament wind.- ings F2 areconnected by the leads 62 and 6ft to the conductors do and 63respectively, which connect with filaments 76 and 72. The lilamentwindings F3 connect by the leads 74 and 76 to the filaments 78. Theleads 76 each connect to a common terminal of the conductor 80 whichextends from the right hand terminal of the secondary winding S in eachcase, through the series capacitor Cp to one side of the filament 78.The shunting lcondenser Cs in each case connects from the lead 68 to thesame side of the filament 73 to which lead 80 is connected.

Small shunts 82 and 84 are shown in both apparatuses, but it is notintended that all structures will have both shunts. ln addition, a pairof slots or bridged gaps are shown in the central winding leg lei, oneat and one at S2. The gap 8S is slightly to the right of the center ofthe transformer 5.2, and the gap do is shorter in width and locatedsubstantially closer to the primary part P1. Shunts 82 and 8.41 havegaps 81 and 83.

The operation of the apparatus is not substantially different theconventional rapid start circuit, insofar as ignition and operation areconcerned. The energization of the primary winding parts P1 and P2results in small currents flowing in the iilament windings F1, F2 and F3with heating of the lamp lilaments 6), '76, 72 and 7S. The voltageacross the primary P1, P2 induces a voltage in the secondary winding Sthe value of which is approximately the turns ratio, reduced somewhat bythe reduction of coupling from 100%. The voltage from the secondarywinding S is combined with the voltage across the primary P1, P2 due tothe auto-transformer arrangement, and the total voltage is more thansufficient to ignite lamp L1. rhereatter current iiows through the lampL1, the by-pass branch including condenser Cs and the lead Sii. This lowof current through Cs which has a high capacitive reactance produces avoltage drop across Cs which is sufcient to ignite lamp L2. As soon aslamp L2 ignites, its impedance is substantially lower than the reactanceof the by-pass branch and hence practically all of the current iowsthrough the lamps in series.

The total power factor of the circuit is controlled by the inductanceand leakage reactance balanced against the capacitive reactance, thelatter being primarily controlled by the condenser C11. in recent yearsthe ratio of capacitive to inductive reactance in apparatus of this typehas been increased from the former value of about two to one to highervalues. In this apparatus, the ratio approaches three to one, which isstill a leading circuit, giving rise to problems of wave shapedistortion and the like, but providing economies in construction andoperation.

n the case of the parallel circuit 10, the total number of turns of wirein each of the primary parts P1 and P2 is equal to twice the number' ofturns of wire in each of the primary parts P1 and P2 of the seriescircuit fr0 because the total primary voltage is not divided between theparts as in the case of the series circuit. The current in each primarypart of the circuit 10 is half of the current through the primary partsof the circuit .10 and hence the wire used may be much liner. As amatter of practicability, it was found that there was some advantageinsofar as current carrying capacity in the parallel case. All of theabove assumes the same secondary winding.

The shunts 82 and 84 were formed of small strips of electrical sheetsteel, about three or four in number, to give a total thickness of about.100 inch, shaped to t between windings. These pieces are of a width toprovide total air gaps of approximately .040 inch at the shunts, theirlength being equal to that of the stack 0f laminations. An assemblage ofthese strips is shown in Fig. 4.

The division of the primary into its parts P1 and P2 and location atopposite ends of the secondary S gives more than suiiicient couplingbetween the windings, and thus the central slot 88 gives the control ofleakage reactance and coupling which renders the structure advantageous.

It serves also to prevent saturation and corrects wave shape. Theadditional slot S6 decreases the coupling with the primary part P1 andthus increases the leakage reactance at the left end of S. While theexact nature of the theory of operation is not completely understood, ithas been found that the arrangement shown, with the central gap 88slightly oit center, and the gap S6 toward one of the primary parts,gives highly satisfactory results. Note that the gap 86 is shorter intransverse dimension. In certain cases gap 86 has been eliminated withgood results, and also one or the other of the shunts 82 and 84 may beeliminated.

The basic structure requires at least the center gap 88 which is ofsubstantially greater length (along the length of the central windingleg 14) than usual for bridged gaps of the type heretofore used for Waveshape correction. This provides the advantages in combination with thesplit primary to give the goed coupling, proper leakage reactance andgood wave shape correction.

The following examples of practical versions of the apparatus are fortwo Power Groove rapid-start lamps, of the rating set forth above. Theconfiguration of the laminations is to scale, the overall length being11.6 inches, the overall width being 3.05 inches. Other core dimensionsare length of the windings P1 and P2 along the core-1.4 inches; lengthof the winding S-7.52 inches; width of side legs 18, end bridgingportion 16, short arms 26-.515 inch; width of windows-.475 inch. Thebridged gaps are both .190 inch in length, the gap 86 being .6 inch intransverse dimension and the gap 88 being .768 in transverse dimension.The center of the gap or slot S6 is 3.5 inches from the left hand end ofthe core, and the center of the gap SS is 5.5 inches from theA righthand end of the core. The shunts 84 were in each case made up of fourpieces of .O25 thickness steel .430

by 1.5 inches in dimensions. inches to 1.5 inches.

The stack height was 1.25

P2 4370 turnsof21gauge wire-carrying lf-.4-amperes,

S 1560 turns of 181/2 gauge Wire carrying 2.8 amperes.

"Forapparatus iti', series primary parts:

P1 173 turns of 18 gauge wire carrying 2.8 amperes. P2 186 turns of 17gauge wire carrying 2.8 amperes. S 1628 turns of 181/2 gauge wirecarrying 2.8 amperes.

vOpen circuit voltage across the windings for both cases was 525 volts,so that the open circuit for S alone was 405 volts. The condensers usedin the circuits were the same in both cases. The shunting condenser CShad a capacity of .075 microfarad and a voltage rating. of 575 voltsR.M.S. The series condenser is 6.8 microfarads with a rating of 525volts R.M.S. Usually the two condensers are mounted in the samecontainer and have a common terminal.

The two primary parts P1 and P2 need not have the same number of turns,but in the case of the parallel circuit 10, there must be balancebetween these parts in order that both primary parts draw the samecurrent to avoid localized heating and possible excessive magnetizingcurrent in one or the other. Equal turns, and/or adjustment of theshunts enable this balance to be achieved.

Note that the turns ratio of secondary to primary turns is quitesubstantial, being approximately 5 to 1, and that the secondary windingS has a length greater than half the length of the entire core, thewinding occupying the greater portion of the window space of the core.

In Fig. 5 there is illustrated another apparatus, identied by thereference character which differs from the apparatus of Fig. 2 inseveral respects. The primary parts P1 and P2 instead of being connectedin auto-transformer relationship with the secondary winding S aretogether connected in straight voltage step-up transformer relatlonshiptherewith. The voltage across the primary winding P1, P2 in this circuitdoes not add to the open circuit or operating voltages of the secondarywinding S. In certain instances this form of circuit may be desired. Theprimary parts are connected in series by way of lead 48 and the oppositeterminal of primary. part P2 is connected by lead 52 to one side of theline, while the lead 44 of the primary part is connected to the otherside of the line. The secondary winding S is thus connected directlyacross the series connected lamps by leads 58 and Sti.

`A modified arrangement of i'ilament windings is also illustrated inthis case, to demonstrate that variations in this phase of the circuitare also possible. All three filament windings F1, F2 and F3 are coupledwith the primary part P1 which may be ot physical character diiierentfrom that of winding P2 to enable this arrangement. Filament winding F1uses lead S6 and common lead 58 to energize filament 60 and lamentwindings F2 and F3 are connected like those of Figs. 2 and 3.

But for the need for a somewhat higher turns ratio, and those diierencesmentioned above, the structure is quite similar to that of Fig. 2.Modication of the primary winding connections to parallel primary partsis practically identical to the modification of Fig. 2 to Fig. 3, andhence it is believed not essential to illustrate this.

The transformer structure 12 illustrated in Fig. 6 is interchangeablewith that of Fig. 1 insofar as basic construction and operation areconcerned. Instead of being formed from three stacks of laminations heldtogether by clamps or the like, this is a forced core type of structure.There is an outer rectangular frame having side legs 1% and end legs 1.6and 26, formed of integral rectangular laminations held together byrivets or grommets as indicated. The central winding leg 14 is alsoformed of .a stack of laminations which are punched from the outerlaminations during manufacture to assure close iit former 12, exceptthatassembly may be somewhat different. Here, the windingsare allassembled to the winding leg ifi in advance of assembly, by sliding thecoils over the winding leg. For example, the right hand shunt 8d may beformed of inward extensions integral with the side legs iti meetingoutward extensions integral with the central windingv leg id at gapsgli, so that the'winding P2 can be slipped onto central winding leg fromits right hand end and will seat properly. The other windings aresiipped on from the other end. Shunt S2 is shown here wholiy formed fromintegral extensions of the side iegs i5 stopping short of the centralwinding leg to form gaps 331.

incidentally, in all structuresv it was found that the length ot' gapsof shunts 32 and d' is not critical.

Note that in the transformer il the filament windings F1, F2 and F3 areall in the window 221i. Other arrangements are obviously feasible, suchas tor example, having four filament windings, two closely coupled toeach of the primary parts, respectively.

It is believed the invention has been sufficiently described to enablethose skilled in this art to make and use the same, and it is pointedout that considerable variations can be made within the scope of theclaims appended hereto, without sacrificing any of the features andadvantages of the invention. Y

What it is desired to secure by Letters Patent of the United States is:

1. Apparatus for igniting and providing the operating voltages for atleast one gaseous discharge device from a source of A.C. voltageinsuiicient to ignite said gaseous discharge device, which comprises, anelongate iron core having an elongate winding leg and at least oneparallel side leg forming therewith a plurality of windows, atransformer mounted on the coreV and having a primary winding formed oftwov parts and a secondary winding, the secondary winding having aphysical length greater than half the length of said winding leg andbeing mounted in one of said windows on said winding leg with the partsof said primary winding mounted in others of said windows coaxially withsaid secondary winding on said winding ieg and being located on oppositeends of said secondary winding, the primary winding adapted to beconnected across said source and being in voltage step-up transformerrelationship with the secondary winding, means including electricalleads for connecting said gaseous discharge device at least with saidsecondary winding to be subject to the voltages of said transformer, anda bridged gap in said core substantially at the center of said secondarywinding and completely enclosed therein.

2. Apparatus as ciairned in claim 1 in which said primary parts are inparallel with one another.

3. Apparatus as claimed in claim 1 in which said primary parts are inseries with one another.

4. Apparatus as claimed in claim 1 in which said electrical leads have acapacitive reactor therein, the reactance of which is substantiallygreater than the total inductive reactance of the transformer.

5. Apparatus for igniting and operating at least one gaseous dischargedevice from a source of A.C. voltage insuicient to ignite said gaseousdischarge device, which comprises, a shell-type iron core having acentral winding leg and side framing legs, a transformer comprising asecondary winding and a primary winding mounted on said core with theprimary winding formed of two parts and the secondary winding beingcoaxial with the central winding leg and having the two parts located atopposite ends thereof, the primary winding adapted to be connectedacross said source, means including electrical leads for connecting saidprimary winding and secondary winding in voltage step-up transformerrelation with one another and at least said secondary winding acrosssaid gaseous-,discharge device, a siot in the central winding legapproximately at the center thereof completely within. said secondarywindingand at least ashunthaving high reluctance gap between one of saidparts and said secondary winding.

6. Apparatus as claimed in claim in which there is a second similarshunt between the second of said parts and said secondary winding.

7. Apparatus as claimed in claim 5 in which there is a second slot insaid central winding leg, also completely within said secondary winding,but located substantially closer to one part of said primary windingthan the other.

8. Apparatus as claimed in claim 5 in which said primary parts areconnected in parallel with one another.

9. Apparatus as claimed in claim 5 in which said primary parts areconnected in series with one another.

10. Apparatus for igniting and operating a pair of gaseous dischargedevices from a source of A.C. voltage, which comprises, an elongate ironcore having a central winding leg, a transformer mounted on said coreand having a secondary winding and a primary winding all mountedcoaxially along said central winding leg, said primary winding havingtwo parts and the secondary winding being physically located betweensaid parts, means including electrical leads and a series capacitorforconnecting said primary and secondary windings in voltage aidingauto-transformer relationship and across both of said gaseous dischargedevices in series, and said last mentioned means including a capacitorshunting one of said gaseous discharge devices, the primary windingadapted to be connected with said source, and means in said centralwinding leg for adjusting the coupling of said primary parts andsecondary and the leakage reactance of said secondary winding comprisingat least one relatively large transverse slot substantially in thecenter of the said central winding leg between the ends thereof beneaththe secondary winding.

11. Apparatus as claimed in claim in which there is at least one gappedshunt between said secondary winding and one of said primary parts.

12. Apparatus as claimed in claim 10 in which there is a secondtransverse slot in said winding leg spaced from said one slot closer toone of said primary parts, and also beneath said secondary winding.

13. Apparatus as claimed in claim 12 in which there are gapped shuntsbetween each ot said primary parts and said secondary winding.

14. Apparatus of the character described adapted to be energized from anA.'C. source, comprising, a pair of gaseous discharge devices connectedin series and having a starting capacitance shunting one of saiddevices, an elongate iron core having a central windinv leg, atransformer mounted on said core and including a primary winding adaptedto be connected to said source and a secondary winding of a number ofturns many times the number of primary turns, said windings beingmounted coaxial with said central winding leg along the length thereof,the length of the core being several times its Width and there beingrelatively narrow windows confning said windings whereby the physicallength of said secondary winding is greater than half the length of saidcore, the primary winding and secondary winding being connected involtage aiding auto-transformer relationship and across said pair ofgaseous discharge devices and there being a series condenser in saidconnection, the primary winding being formed of two physically separatedparts located on opposite ends of said secondary winding at the ends ofsaid central winding leg, and said central winding leg having atransverse slot with closed ends located in the center beneath saidsecondary winding.

15. Apparatus as claimed in claim 14 in which there is another similarslot, albeit of shorter Width in said winding leg spaced between the rstslot and one end of the said secondary winding.

16. Apparatus as claimed in claim 14 in which said primary parts areconnected in series with one another.

17. Apparatus as claimed in claim 14 in which `said primary parts areconnected in parallel with one another.

18. Apparatus as claimed in claim 14 in which gapped shunt means areprovided between each of said primary parts and the secondary winding.

19. Apparatus of the character described adapted to be energized from asource of A C. voltage, comprising, a pair of gaseous discharge deviceseach having a filament at opposite ends thereof, and the devices beingconnected in series with a condenser shunting one of the devices, atransformer having a secondary winding and a primary winding connectedin voltage step-up transformer relation and at least the secondary beingin connection across said pair of devices and having a series condenserin said connection, a plurality of lament windings coupled with saidprimary winding, and an iron core mounting said transformer, saidsecondary winding having a substantially greater length than width, saidcore having a central winding leg, said secondary winding being mountedcoaxial of said central winding leg, said primary winding being formedof two parts and there being a part located adjacent the opposite endsof said secondary also coaxial of said central winding leg, said centralwinding leg having a central bridged gap beneath said secondary winding,and gapped shunt means between said secondary winding and at least oneof said primary parts, said primary winding adapted to be connected tosaid source.

20. Apparatus as claimed in claim 19 in which said core has elongatewinding windows and the said secondary winding is disposed in onewindow, and each of the primary parts in other windows, and the saidfilament windings also disposed in the windows of said primary parts.

21. Apparatus for igniting and providing the operating voltages for atleast one gaseous discharge device from a source of A.C. voltageinsufficient to ignite said gaseous discharge device, which comprises,an elongate iron core having an elongate winding leg and at least oneparallel side leg forming therewith a plurality of windows, atransformer mounted on the core and having a primary winding formed oftwo parts and a secondary winding, the secondary winding having aphysical length substantially greater than half the length of saidwinding leg and being mounted in one of said windows on said winding legwith the parts of said primary winding mounted in Others of said windowscoaxially with said secondary winding on said winding leg and beinglocated on opposite ends of said secondary winding, the primary windingadapted to be connected across said source and having anauto-transformer connection with said secondary winding, means includingelectrical leads for connecting said gaseous discharge device with saidsecondary and primary windings to be subject to the combined aidingauto-transformer voltages thereof, and a bridged gap in said coresubstantially at the center of said secondary winding and completelyenclosed therein.

22. Apparatus for igniting and operating at least one .gaseous dischargedevice from a source of A.C. voltage msuicient to ignite said gaseousdischarge device, which comprises, a shell-type iron core having acentral winding leg and side framing legs, a transformer comprising asecondary winding and a primary winding mounted on said core with theprimary winding formed of two parts and the secondary winding beingcoaxial with the central winding leg and having the two parts located atopposite ends thereof, the primary winding adapted to be connectedacross said source, means including electrical leads for connecting saidprimary winding and secondary winding in voltage aiding auto-transformerrelation with one another and across said gaseous discharge device, aslot in the central winding leg approximately at the center thereofcompletely within said secondary winding, and at least a shunt having ahigh reluctance gap between one of said parts and said secondarywinding.

l23. Apparatus of the character described `adapted toa-be energized froma source of A.C. voltage, comprising, a` pair of gaseous discharge-vdevices each havingaV lament at opposite ends thereof, and thedevicesbeing connected in series with a condenser shuntingone of the devices, atransformer having a secondary Winding and a primary Winding connectedin voltage aiding autotransformer relation. and across said pair ofdevices and having a series condenser in said connection, a plurality offilament windings coupled with said primary winding and an iron coremountingfsaid transformer, said secondary-Winding havingv asubstantially greater length than Width, said core yhaving a centralWinding leg, said secondary Winding being mounted coaxial of saidcentral Winding leg, said primary winding being formed of two parts and"there being a party located adjacent the opposite ends ,oi saidsecondary also coaxial of said central Winding leg,

said central winding leg having a central bridged gap beneath saidsecondary winding, and gapped shunt means between said secondary windingand at least one 'of 'Said primary parts, said primary Winding adaptedto be connected to said source.

References Cited in the le of this patent UNITED STATES PATENTS

